The Chemistry of the Estrus Producing Hormone.

Abstract

The publications of Allen and Doisy in which estrin (folliculin) has been shown to be present in the follicular fluid of castrated mice, 1 have been followed by publications from other authors who detected this hormone in the ovary and, more particularly, in the placenta. Loewi and his coworkers have since shown the hormone to be present in the urine of pregnant women, 2 and Doisy and Veler have devised a convenient method for extracting it. 3

Little seems to be known of the chemistry of this hormone. Earlier authors considered estrin to be a lipoidal substance present in the non-saponifiable fraction (sterol fraction). Somewhat later several investigators (particularly Zondek 4 ) prepared the substance in a water-soluble form. No detailed description of the method used in preparing the substance in water-soluble form seems to have been given; and it seems somewhat difficult to understand how a substance first described as lipoidal in character can be rendered entirely water-soluble by an extraction process.

Some observations made by the writer during the past year may throw light on the matter. It has been found that estrin is very sparingly soluble even in hot water, and that most of the hormone occurs in the free state in the ovary, placenta or urine. Saponification is not necessary. The reason why the hormone has been supposed to reside in the unsaponifiable (cholesterol) fraction is because it forms salts with strong alkalies which are fairly well soluble in ether. Estrin forms soluble sodium, potassium, ammonium, and barium salts. Making use of the property just described, estrin fractions weighing 0.01 mg. per rat unit are easily obtainable. Such preparations show an acidity equivalent to 43.2 cc. of N/10 sodium hydroxide per 100 mg. of substance.